The present invention relates to motor vehicles and in particular to a crankcase gas air to fuel ratio correction system.
Systems for monitoring crankcase or ‘blow-by’ gases have been previously proposed. Hagari (U.S. Pat. No. 7,171,960) teaches a control apparatus for an internal combustion engine. In one embodiment of the Hagari control apparatus, an injector is controlled in order to reduce the influence of blow-by gas on the air fuel ratio, thereby further improving the purification performance of the blow-by gas. Hagari teaches the use of an air fuel ratio sensor that is disposed within the exhaust line of the engine. Hagari further teaches the use of a blow-by gas passage and a blow-by gas valve that controls the amount of blow-by gas that may enter back into the intake line of the engine via the blow-by gas passage. Based on measurements made by the air fuel ratio sensor, and calculations performed using an electronic control unit, a correction to the amount of fuel injected using the injector is made so as to maintain a selected air to fuel ratio within the engine even when blow-by gas is present in the intake manifold. Hagari fails to teach the concept of directly measuring the air quality of crankcase gases.
Ahlborn et al. (U.S. Pat. No. 5,911,213) teaches a process for operating an electrostatic filter for a crankcase ventilator. Ahlborn teaches the use of an electrostatic filter that is used to separate oil from crankcase gases. The crankcase gases are supplied to the electrostatic filter, which filters out oil and possibly other contaminates, and produces a purified gas that is further fed to a sensor. The sensor determines the contamination level of the purified gas and then the purified gas is returned to the intake line of the engine. Based on the level of contamination, the voltage of the electrostatic filter can be modified to increase or decrease the amount of filtering performed by the electrostatic filter. Ahlborn further teaches collecting the filtered oil and returning it the crankcase or to a separate collection vessel.
Norrick (U.S. Pat. No. 6,892,715) also teaches a crankcase ventilation system. Norrick teaches a ventilation system for re-introducing blow-by gases in engine systems including turbochargers and after-coolers. In order to prevent contamination of a turbocharger and after-cooler from contaminating particles often found in blow-by gases, the blow-by gases in the Norrick design are routed through a breather port in the crankcase, and through a breather line, to a separate turbocharger or air-compressor. Following this, the compressed blow-by gas is reintroduced into the intake air stream downstream of the turbocharger and after-cooler. Norrick mentions the possibility of adding a sensor at the breather port that monitors the amount of blow-by gases.
Shureb (U.S. Pat. No. 6,779,516) teaches a closed crankcase ventilation system for re-circulating effluent gas stream of an internal combustion engine. Shureb teaches the use of an air-flow monitor inside the ventilation system in order to allow continuous monitoring of engine blow-by gas flow to evaluate the condition of an engine and to diagnose problems associated with increased blow-by gas flow. Shureb teaches the use of the air-flow monitor inside a ventilation system that runs from the crankcase to the engine air intake manifold. Shureb teaches the use of either a turbine air flow meter, or in some cases, a mass flow sensor. Using the mass flow sensor, the system could detect an increase in oil concentration to the effluent gas stream. Although Shureb teaches the use of an air-flow monitor inside a ventilation system for blow-by gases, Shureb does not teach a sensor used for determining air to fuel ratios of the blow-by gases.
Schneider et al. (U.S. Pat. No. 6,575,022) teaches an engine crankcase gas blow-by sensor. Schneider teaches a sensor that measures the pressure of the blow-by gas in order to determine the volume of blow-by gas in an effort to monitor the engine health. Schneider teaches a system where crankcase gases are caused to flow through a venturi that includes high pressure and low pressure taps. The high and low pressure taps are coupled to a differential pressure transducer that produces an output that is proportional to the volumetric flow of crankcase gases through the venturi. In the Schneider design, an inlet port of the venturi is coupled to the interior of the crankcase while the outlet port is coupled to the air intake system of the engine. Schneider does not teach or render obvious the use of other sensors that may be used to monitor the air to fuel ratio of the crankcase gases.
The prior art has additional shortcomings. There is no teaching in the prior art of a ventilation system with sensors used to monitor blow-by gases where the sensors are in communication with a fuel injector or an ignition timing system. There is a need in the art for a system and method that addresses the problems of the prior art.